可编程逻辑器件概述 (15).ppt

EDA技术技术2.CASE语句语句case 语语句的格式如下：句的格式如下：case iswhen =;.;；when =;.;；.when others =;.;；end case;5.2 顺序语句型 例例5-6 用用case语句设计语句设计BCD七段字符显示译码电路七段字符显示译码电路十进制数十进制数A3A2A1A0A3A2A1A0a b c d e f ga b c d e f g显示字符显示字符0 000000000111111011111100 01 100010001011000001100001 12 200100010110110111011012 23 300110011111100111110013 34 401000100011001101100114 45 501010101101101110110115 56 601100110101111110111116 67 701110111111000011100007 78 810001000111111111111118 89 910011001111101111110119 9表表5-2 BCD显示字符真值表显示字符真值表图图5-4 七段数码管引脚图七段数码管引脚图LIBRARY ieee;use ieee.std_logic_1164.all;use ieee.std_logic_unsigned.all;ENTITY SEG7 ISPORT(num:INstd_logic_vector(3 downto 0);led:OUT std_logic_vector(6 downto 0);END SEG7;ARCHITECTURE fun OF SEG7 IS BEGIN process(num)begin case num is when 0000 =led ledledledledledledledledledled=0000000;end case;end process;END fun;谢谢！